Nanosecond magnetization dynamics during spin Hall switching of in-plane magnetic tunnel junctions

TL;DR

This study investigates nanosecond-scale magnetic switching in in-plane magnetic tunnel junctions driven by the spin Hall effect, revealing the crucial role of the Oersted field and micromagnetic curvature in enhancing switching speed and reliability.

Contribution

It demonstrates the impact of the Oersted field and magnetic curvature on fast spin Hall switching, supported by experiments and micromagnetic simulations, providing new insights into magnetic reversal mechanisms.

Findings

Fast and reliable magnetic reversal facilitated by the Oersted field.

Micromagnetic curvature enhances energy efficiency during switching.

Sign of the Oersted field critically influences switching dynamics.

Abstract

We present a study of the magnetic dynamics associated with nanosecond scale magnetic switching driven by the spin Hall effect in 3-terminal nanoscale magnetic tunnel junctions (3T-MTJs) with in-plane magnetization. Utilizing fast pulse measurements in a variety of material stacks and detailed micromagnetic simulations, we demonstrate that this unexpectedly fast and reliable magnetic reversal is facilitated by the self-generated Oersted field, and the short-pulse energy efficiency can be substantially enhanced by micromagnetic curvature in the magnetic free layer. The sign of the Oersted field is essential for this enhancement --- in simulations in which we artificially impose a field-like torque with a sign opposite to the effect of the Oersted field, the result is a much slower and stochastic switching process that is reminiscent of the so-called incubation delay in conventional 2-terminal spin-torque-switched MTJs.